Wireless Communication Terminal and its Control Method

ABSTRACT

In the prior art, the initialization process for communication between a wireless communication terminal and a base station is executed by activating the wireless communication terminal with a built-in battery. As a result, the problem is posed that a great amount of power is consumed during the initialization process and the battery of the wireless communication terminal is consumed early. Especially, in the case where the network configuration is required to be changed frequently, the life of the battery of the wireless communication terminal is extremely shortened resulting in a low practical value. In view of this, a passive RFID is mounted on the wireless communication terminal, and the initialization process is executed by the power supplied from the base station using the RFID interface. As a result, the battery consumption of the wireless communication terminal can be prevented in the initialization process.

TECHNICAL FIELD

This invention relates to a communication technique using a wirelesscommunication terminal, or in particular to a technique for initialconfiguration process of the communication between the wirelesscommunication terminal and a base station.

BACKGROUND ART

At the time of the construction and maintenance work for a compactwireless communication terminal used in a communication network using ashort-range radio such as the sensor net, the process of registering andinitial configuration a new wireless communication terminal includingthe mutual authentication and the exchange of the encryption keys forcommunication between a new wireless communication terminal and a basestation is required to be executed. This initial configuration processrequires the process such as the authentication with a public keycryptography, key exchange, generation of a random number and the writeoperation into a memory. These processes involve a large amount ofarithmetic operation, and therefore, may be difficult to execute for thecompact wireless communication terminal operated by the solar batterycell or vibration to electric energy converter. With a wirelesscommunication terminal using a small cell such a button battery cell, onthe other hand, the life is extremely shortened, and therefore, theproblem of an increased maintenance cost is posed. In the case where thecommunication between the base station and the wireless communicationterminal is initialized using another server, etc. in advance, on theother hand, preparatory operations are required to determine the basestation for the destination and distribute the key safely to theparticular base station in advance. In view of the fact that the networkconfiguration is generally required to adapt to the situation of theplace of installation as occasion demands, however, the aforementionedsetting steps lack the operation flexibility and low in workingefficiency. Also, in the case where the system configuration for thereplacement of a base station is changed due to a fault, the job ofrecovering and resetting the wireless communication terminal connectedto the particular base station is generated.

DISCLOSURE OF THE INVENTION

(Solving Means)

According to this invention, the aforementioned problem is solved bymounting a passive wireless tag (radio frequency identification;hereinafter referred to as RFID) on a wireless communication terminaland executing the registration and initialization process by theinteractive communication between the RFID of the wireless communicationterminal and the base station. In this system, power is supplied to theRFID from the base station at the time of registration andinitialization, and therefore, the process can be executed withoutconsuming the battery cell of the wireless communication terminal.

Between the wireless communication terminal and the base station, theprocess of initialization of the communication is executed bycommunication and power supply using the RFID interface. By supplyingpower from the base station at the time of initialization in this way,the initialization process using the public key cryptography is madepossible even for the small sensor node operated by the button cell orthe vibration to electric energy converter. Also, a high durability canbe realized even for a wireless communication terminal used under asevere environmental condition for lack of a contact interface.

A specific terminal configuration according to the invention concerns awireless communication terminal used for a communication systemconfigured of the wireless communication terminal, a base station and aserver connected to the base station through a communication network,characterized by a wireless communication function for communicationwith the base station and a passive wireless tag, wherein thecommunication between the wireless communication terminal and the basestation is set by use of the communication between the passive wirelesstag mounted on the wireless communication terminal and the base station.

The terminal is preferably configured to store the information preparedby the process of setting in a memory for conducting the communication.As a specific example, the passive wireless tag may have a nonvolatilestorage medium which may record an identification number of the wirelesscommunication terminal and an encryption key unique to the wirelesscommunication terminal. As an alternative, the passive wireless tag mayhave a volatile memory such as SRAM, in which an identification numberof the wireless communication terminal and an encryption key unique tothe wireless communication terminal may be stored.

Also, the encryption key unique to the wireless communication terminalmay include a public key, a private key and a certificate forauthentication by the public key cryptosystem. Further, the encryptionkey unique to the wireless communication terminal may include anencryption key for the symmetric key cryptosystem. As a wirelesscommunication function, for example, a communication scheme based on awell-known protocol such as wireless LAN can be used.

The wireless communication terminal includes a battery for supplying theoperating power. The initialization process is executed by the passivewireless tag receiving the power supplied from the reader/writer of thewireless tag, while the other normal operation is performed by the powersupplied from the battery. As a result, the battery power is notconsumed for the initialization process which consumes a large power,and therefore, the maintenance intervals or the life of the wirelesscommunication terminal can be lengthened. Further, the result of theinitialization process is recorded in the nonvolatile storage medium,and during the normal operation, the result (for example, theidentification number of the base station, encryption key forcommunication, etc.) is read from the nonvolatile storage medium toconduct the communication.

Also, the scope of this invention covers a control method for acommunication system configured of a wireless communication terminal, abase station and a server connected with the base station through acommunication network, wherein the wireless communication terminal hasthe wireless communication function for communication with the basestation and the passive wireless tag and wherein the process of settingthe communication between the wireless communication terminal and thebase station is executed using the communication between the passivewireless tag mounted on the wireless communication terminal and the basestation.

Further, according to this invention, there is provided a wirelesscommunication system configured of a wireless communication terminal, abase station and a server connected with the base station through acommunication network, wherein the wireless communication terminalincludes the wireless communication function for communication with thebase station and the passive wireless tag, and wherein the process ofsetting the communication between the wireless communication terminaland the base station is executed using the communication between thepassive wireless tag mounted on the wireless communication terminal andthe base station, characterized by having the wireless tag read/writefunction for communication with the passive wireless tag mounted on thewireless communication terminal.

According to another aspect of the invention, a wireless communicationterminal, used for a communication system configured of the wirelesscommunication terminal, a base station and a server connected to thebase station through a communication network, includes a power supply, acontroller, a wireless interface, a nonvolatile memory, an antenna, aRFID unit having a power generating circuit for generating the powerfrom the signal received by the antenna and an internal bus connectingthese parts thereby to operate in two modes. In the first mode, usedmainly for initialization, the controller is operated with the powergenerating circuit as a power supply and the result of the operation isstored in a memory such as a nonvolatile memory. During this operation,the power is generated from the signal received by the antenna and usedfor the controller, the write operation into the memory and theoperation of the wireless interface, and therefore, the power supplysuch as the battery need not be used, thereby leading to the advantagethat the restriction of power consumption is not required for thecomplicated calculations and process (encryption/decryption process andthe write operation into the memory) for initialization.

In the second mode, which involves the normal communication operation,the controller is operated using a power supply such as a battery or asmall generator, and the communication conducted with the base stationthrough the wireless interface using the information stored in thememory during the first mode. Two controllers including a firstcontroller and a second controller may be provided for the respectivemodes.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram showing the configuration of a communicationsystem including a wireless communication terminal and a base stationaccording to this invention.

FIG. 2 is a configuration diagram showing the contents recorded in anonvolatile memory in a RFID mounted on a sensor node.

FIG. 3 is a configuration diagram showing the contents recorded in anonvolatile memory of the base station.

FIG. 4 is a flowchart showing the steps of the initialization processaccording to the embodiment shown in FIG. 1.

FIG. 5 is a configuration diagram showing the contents recorded in anonvolatile memory in a RFID mounted on the wireless communicationterminal according to a second embodiment of the invention.

FIG. 6 is a configuration diagram showing the contents recorded in anonvolatile memory of the base station according to the secondembodiment of the invention.

FIG. 7 is a flowchart showing the steps of the initialization processaccording to the second embodiment of the invention.

FIG. 8 is a block diagram showing another example of the configurationof a wireless communication terminal system according to an embodimentof the invention.

BEST MODE FOR CARRYING OUT THE INVENTION Embodiment 1

A first embodiment of the invention is explained below with reference toFIGS. 1, 2, 3 and 4.

FIG. 1 is a diagram schematically showing a communication systemconfigured of a wireless communication terminal 1, a base station 2, acommunication network 3 and a server 4.

The wireless communication terminal 1 has mounted thereon a controller11, a short-range wireless interface 12, a sensor 17 and a RFIDreader/writer 13, which are interconnected by an internal bus 14. Thewireless communication terminal 1 is connected also to a RFID 18 througha RFID reader/writer 13. The RFID 18 has a contact-type interface and anoncontact-type interface. The wireless communication terminal 1 furtherincludes a power supply 16 for supplying power to operate each of theaforementioned parts. The power supply 16, though not specificallylimited, is configured of a disposable battery cell such as a buttoncell or a dry cell, a charge battery such as a lithium-ion cell or apower generating device having a solar cell or a vibration to electricenergy converter. The RFID 18 includes a controller 181, a nonvolatilememory 182, an antenna 183, a power generating circuit 184 and a serialinterface 185. The RFID 18 further includes a power supply line 187 forsupplying power from the RFID reader/writer of the wirelesscommunication terminal 1, a power supply line 188 for supplying thepower generated by the power generating circuit 184 from an antenna, apower supply select circuit 186, a power supply line 189 and a RFcircuit 190 for executing the process such as converting between theanalog signal transmitted to or received from an antenna and the digitalsignal processed by the controller. The power supply line 189 suppliespower to the controller 181 and the nonvolatile memory 182.

According to a preferred embodiment, only the RFID 18 shown in FIG. 1 isoperated of all the parts of the wireless communication terminal duringthe initialization. Specifically, during the initializing operation, thecontroller 11 is not operated and the controller 181 controls theinitialization process. The initialization process for communication isexecuted in its entirety in the RFID 18, and the information thereof isrecorded in the nonvolatile memory 182. The power for operation duringthe initialization is supplied from the power generating circuit 184.

During the normal operation, on the other hand, the controller 181 isnot operated but the controller 11 works. In starting the communicationas normal operation (by short-range radio), the controller 11 reads thefollowing information used for the short-range wireless communicationfrom the nonvolatile memory 182 of the RFID 18 through the serialinterface 185. Specifically, the information to be read include theidentification number of the base station and the encryption key forcommunication (shared with the base station 2 by the key exchangeprocess 536 described later). As described above, during theinitialization process, the RFID 18 is operated by the power supply 184,and during the normal operation, the entire wireless communicationterminal 1 including the RFID 18 is operated by the power supply 16 (theRF circuit 190 is not operated). The aforementioned power supplies areswitched by operating a switch 186 under the control of the controller11. The base station 2 includes a controller 21, a short-range wirelessinterface 22, a RFID interface 23, a nonvolatile memory 24 and acommunication interface 25.

The server 4 holds a list of identification numbers as an invalidationlist 41 describing the invalidated wireless communication terminals. Thecontents of the invalidation list 41, though not specifically limited,include the identifiers of the wireless communication terminals lost bytheft, loss, etc.

FIG. 2 is a diagram showing the information recorded in the nonvolatilememory 182 of the RFID 18 mounted on the wireless communication terminal1.

FIG. 3 is a diagram showing the information recorded in the nonvolatilememory 24 of the base station 2.

The nonvolatile memory 182 of the RFID 18 contains the identificationnumber 191 of the wireless communication terminal, the identificationnumber 191 of the wireless communication terminal, the private key 192,the public key 193, the certificate 194 and the public key 195 of thecertificate Authority. The nonvolatile memory 24 of the base station 2contains the identification number 241 of the base station, the privatekey 242 of the base station, the public key 243 of the base station, thecertificate 244 and the public key 245 of the certificate Authority. Theauthentication method using the public key cryptography is a well-knowntechnique (Alfred J. Menezes, Paul C. van Oorschot, Scott A. Vanstone:“Handbook of Applied Cryptography”, CRC Press, 1996, ISBN:0-8493-8523-7, Chapter 10), and therefore, not described in detailherein.

An example in which the information used for communication are stored inthe nonvolatile memory 182 such as the flash memory (trade mark) isdescribed above. In this example, power is not required to be suppliedto the memory after the information is written in the memory. This leadsto the advantage that the power consumption of the memory can be savedand the power supply is not required to be controlled. The configurationof the invention, however, is not limited to this, and the informationcan be stored also in any of other storage media such as a compact harddisk device and a volatile semiconductor memory. As an example, theinformation can be stored in a volatile memory such as the SRAM built inthe controller 181. In this case, the volatile memory is required to bekept supplied with power. During the period when no power is suppliedfrom the power generating circuit 184 of the RFID, therefore, power isrequired to be supplied by the power supply 16. This power supplyswitching operation can be controlled by the controller 181.

With reference to FIG. 4, the steps of the initialization process forcommunication between the wireless communication terminal 1 and the basestation 2 is explained. The RFID 18 mounted on the wirelesscommunication terminal 1, upon detection of the communicability bydetecting the radio wave from the RFID of the base station, transmits aconnection request message 521. The connection request message 521contains the identification number 191 of the wireless communicationterminal 1 read from the nonvolatile memory 182, the public key 193 andthe certificate 194. The base station 2, upon receipt of the connectionrequest message 521, executes the process 522 for confirming thecertificate 194 using the public key 245 of the certificate Authority.Upon confirmation of the legitimacy of the certificate 194, the basestation 2 transmits a random number 523 to the RFID 18. The controller181 of the RFID 18 executes the encryption process 524 using the privatekey 192 for the random number 523, and prepares and transmits a responsemessage 525 to the base station 2. The base station 2 decodes theresponse message 524 with the received public key 193 of the RFID, andchecks to see whether it coincides with the original random number ornot. In this way, the base station confirms whether the RFID of theother party of communication has the private key 192 or not. Next, thebase station requests the server for an invalidation list (527), and theserver, accessing (528) the invalidation list 41, transmits the resultto the base station 2 (529). The request can use the identificationnumber 191 transmitted from the RFID. The base station 2, uponconfirmation that the RFID is not invalidated, transmits a connectionpermission message 530 to the RFID. The connection permission message530 contains the identification number 241 of the base station, thepublic key 243 of the base station and the certificate 244. The RFIDexecutes the process 531 for confirming the certificate 244 using thepublic key 195 of the certificate Authority. The RFID 18, uponconfirmation of the legitimacy and validity of the certificate 244,transmits the random number 532 to the base station 2, which in turnexecutes the encryption process 533 using the private key 242 andreturns a response message 534. The RFID performs the decode operationwith the received public key 243 of the base station and checks whetherit coincides with the original random number or not. In this way, theRFID confirms that the base station 2 constituting the other party ofcommunication has the private key 242. Through the steps describedabove, the base station 2 and the RFID confirm the legitimacy of theother party of communication with each other. After that, the keyexchange process 536 is executed, and the encryption keys 192, 242 forcommunication come to be shared by the base station 2 and the RFID 18.The method of execution of the key exchange process is a well-knowntechnique (Douglass R. Stinson: “Cryptography: theory and practice”, CRCPress LLC, 1995, Chapter 8), and therefore, is not described in detail.

The process described above is executed by the communication through theRFID interface between the wireless communication terminal 1 and thebase station 2. The power for this operation is generated by convertingthe signal (electromagnetic wave) supplied from the base station 2through the power generating circuit 184, and the communication can beinitialized without using the power supply 16 of the wirelesscommunication terminal 1.

In the case where the distance between the place of installation of thewireless communication terminal and the base station is larger than thecommunicable distance of the RFID, the wireless communication terminal 1is temporarily placed near the base station 2 during the initializationprocess, and after the initialization process, installed at the originalplace of installation, after which the communication is conducted withthe base station by the short-range wireless communication. In this way,the method according to this invention can be implemented.

Embodiment 2

Next, a second embodiment is explained with reference to FIGS. 1 and 5,6, 7.

FIG. 5 is a diagram showing the contents recorded in the nonvolatilememory 12 in the RFID 18 mounted on the sensor node. The identificationnumber 191 of the wireless communication terminal, the authenticationkey 196 of the wireless communication terminal and the authenticationkey 197 of the base station are recorded in the nonvolatile memory 182in the RFID 18.

FIG. 6 is a diagram showing the contents recorded in the nonvolatilememory 24 of the base station 2. The identification number 241 of thebase station and the authentication key 242 of the base station arerecorded in the nonvolatile memory 24 of the base station 2.

With reference to FIG. 7, the steps for initialization by communicationthrough the RFID interface between the wireless communication terminal 1and the base station 2 are explained below. The RFID 18 mounted on thewireless communication terminal 1, upon establishment of the physicalcommunication by detecting the radio wave from the RFID of the basestation, transmits a connection request message 551. The connectionrequest message 551 contains the identification number 191 of thewireless communication terminal 1. The base station 2, upon receipt ofthe connection request message 551, transmits a connection requesttransfer message 552 to a server 4. The server 4, upon receipt of theconnection request transfer message 552, accesses the terminalinvalidation list 42 and checks to see whether the connection requestingterminal is valid or not (553). In the case where the connectionrequesting terminal is valid, the server 4 generates and transmits arandom number to the base station (554). The base station 2 transmitsthe received random number to the wireless communication terminal 1(556). The wireless communication terminal 1, using the authenticationkey 196 of itself, encrypts the received random number (557) and sendsit to the base station 2 (558). The base station 2 sends the particularresponse to the server 4 (559), which in turn decodes the response usingthe authentication key of the wireless communication terminal held byitself, and checks to see that it coincides with the original randomnumber thereby to authenticate the wireless communication terminal(560). Once the coincidence is confirmed and the authentication provessuccessful, the server 4 sends the authentication success message 561 tothe base station 2, which in turn sends the connection permit message562 to the wireless communication terminal 1. The wireless communicationterminal 1, after receiving the connection permit message 562, makes theauthentication to checks the legitimacy of the base station 2. For thispurpose, the wireless communication terminal 1 generates and sends arandom number to the base station 2 (563). The base station encrypts therandom number using the base station authentication key 242 (564) ofitself and transmits it to the wireless communication terminal 1 (565).The wireless communication terminal 567 decrypts the random number usingthe base station authentication key 197 recorded in the nonvolatilememory 182 thereby to check to see whether it coincides with theoriginal random number or not. After that, the wireless communicationterminal 1 and the base station 2 execute the process of exchanging thekeys and thus come to share the encryption keys for communication. Themethod of the key exchange process 536 is a well-known technique andtherefore not described in detail.

(Another Example of Configuration of Wireless Communication Terminal andBase Station)

Next, another example of the configuration of the wireless communicationterminal and the base station according to the first and secondembodiments of the invention are is explained.

FIG. 8 is a diagram showing another example of the configuration of thewireless communication terminal and the base station. The wirelesscommunication terminal 6 includes a controller 61, a nonvolatile memory62 and a sensor 66, which are interconnected by an internal data bus 67.Further, the wireless communication terminal 1 includes a RFID antenna63, a power generating circuit 64, a RF circuit 65 for executing suchprocess as converting the analog signal transmitted/received through anantenna and the digital signal processed by the controller and a powersupply line 68. The base station 7 includes a controller 71, anonvolatile memory 72, a RFID interface 73 and a communication interface74.

According to this embodiment, the initialization process between thewireless communication terminal and the base station is carried outsimilarly to the first or second embodiment. The communication betweenthe wireless communication terminal and the base station aftercompletion of the initialization process is conducted through the RFIDinterface. Each logic circuit and the sensor 66 of the wirelesscommunication terminal 6 are supplied with the power generated by thepower generating circuit 64.

INDUSTRIAL APPLICABILITY

The invention according to the present application can be used forwireless communication terminals.

1. A wireless communication terminal used for a communication systemconfigured of the wireless communication terminal, a base station and aserver connected to the base station through a communication network,characterized in that: the wireless communication terminal has mountedthereon a short-range wireless communication function for communicationwith the base station and a passive wireless tag; and the process ofconfiguring the communication between the wireless communicationterminal and the base station is executed using the communicationbetween the passive wireless tag mounted on the wireless communicationterminal and the base station.
 2. The wireless communication terminalaccording to claim 1, characterized in that the passive wireless tag hasa storage medium, in which the identification number of the wirelesscommunication terminal and the cryptographic key unique to the wirelesscommunication terminal are recorded.
 3. The wireless communicationterminal according to claim 2, characterized in that the cryptographickey unique to the wireless communication terminal contains a public key,a private key and a certificate for authentication by the public keycryptosystem.
 4. The wireless communication terminal according to claim2, characterized in that the cryptographic key unique to the wirelesscommunication terminal contains an encryption key according to thesymmetric key cryptosystem.
 5. The wireless communication terminalaccording to claim 1, characterized in that the wireless communicationterminal contains a battery for supplying power at the time ofoperation, and the configuration process is activated by the passivewireless tag receiving power from the wireless tag reader/writer, whilethe power is supplied from the battery during the normal operation. 6.The wireless communication terminal according to claim 5, characterizedin that the result of the configuration process is recorded in thestorage medium, and during the normal operation, the communication isconducted by reading the result of the setting process from the storagemedium.
 7. The wireless communication terminal according to claim 6,characterized in that the storage medium is a nonvolatile storage mediumarranged on the passive wireless tag.
 8. In a communication systemconfigured of a wireless communication terminal, a base station and aserver connected to the base station through a communication network, acontrol method characterized in that: the wireless communicationterminal has mounted thereon a short-range wireless communicationfunction for communication with the base station and a passive wirelesstag, and the process of configuring the communication between thewireless communication terminal and the base station is executed usingthe communication between the passive wireless tag mounted on thewireless communication terminal and the base station.
 9. The controlmethod for the wireless communication system according to claim 8,characterized in that a storage medium is used, and the identificationnumber of the wireless communication terminal and the cryptographic keyunique to the wireless communication terminal are recorded in thestorage medium.
 10. The control method for the wireless communicationsystem according to claim 9, characterized in that the cryptographic keyunique to the wireless communication terminal contains the public key,the private key and the certificate for authentication according to thepublic key cryptosystem.
 11. The control method for a wirelesscommunication system according to claim 9, characterized in that thecryptographic key unique to the wireless communication terminal containsan encryption key according to the symmetric key cryptosystem.
 12. Thecontrol method for a wireless communication system according to claim 9,characterized in that the nonvolatile storage medium of the passivewireless tag is used as the storage medium.
 13. The control method for awireless communication system according to claim 8, characterized inthat the wireless communication terminal includes a battery forsupplying power during the operation, and the configuration process isactivated by the passive wireless tag receiving power from thereader/writer of the wireless tag, while during the normal operation,the power is supplied from the battery.
 14. A base station for wirelesscommunication in a radio communication system configured of a wirelesscommunication terminal, a base station and a server connected to thebase station through a communication network, wherein the wirelesscommunication terminal has a short-range wireless communication functionfor communication with the base station and a passive wireless tag, andwherein the process of configuring the communication between thewireless communication terminal and the base station is executed usingthe communication between the passive wireless tag mounted on thewireless communication terminal and the base station; characterized bycomprising the wireless tag read/write function for communication withthe passive wireless tag mounted on the wireless communication terminal.15. A wireless communication terminal used for a communication systemcomprising the wireless communication terminal, a base station and aserver connected to the base station through a communication network,wherein the wireless communication terminal includes: a battery, acontroller, a wireless interface, a memory, a RFID unit having anantenna and a power generating circuit for generating the power from thesignal received by the antenna, and an internal bus for connecting thefirst controller, the wireless interface and the memory; characterizedin that: in the first mode, the controller is operated with the powergenerating circuit as a power supply, and the result of the operation isstored in the memory, and in the second mode, the controller is operatedwith the power from the battery, and the communication is establishedwith the base station through the wireless interface using theinformation stored in the memory.